The physical forces that determine the binding of proteins to the surface of membranes is a problem of central biological importance through its relationship to signal transduction pathways. We are using continuum electrostatics to study this problem in collaboration with the group of Stuart McLaughlin who is measuring binding affinities as a function of lipid composition and salt. This work has been carried out using a parallel version of DelPhi written by Nir Ben-Tal and implemented on the CM-5.